Is My PC Overheating? Safe CPU Temperatures and How to Check

Short answer: Check your CPU temperature in the BIOS right after startup. A healthy idle reading sits well below 70°C, so 70°C or more at idle points to a problem with the cooler. Under heavy load a CPU can run hot by design. It's only overheating when it reaches its maximum safe temperature and starts slowing itself down.

Hot isn't the same as overheating. PC parts get noticeably warm when they're working hard and some go past 100°C at full load, depending on the chip. What matters is whether your cooler can keep the CPU inside its safe range. Here's how to tell, what the numbers mean and what to fix if yours is running hot.

What counts as overheating?

Your PC is overheating when the CPU cooler can't keep the processor within a safe operating temperature. The CPU is the part to look at first, because it's the one that reacts most visibly.

When a CPU gets too hot it starts thermal throttling: it lowers its voltage and performance to bring the temperature back down. You'll notice it as a drop in performance, usually right when a game or a render is pushing hardest. If throttling doesn't bring things under control quickly, the system triggers Over-temperature Protection (OTP) and shuts down to protect the CPU and the rest of your components.

That's why a PC that switches itself off mid-game is often a heat problem. Our guide to why a PC randomly shuts down walks through how to tell heat from power.

What is a safe CPU temperature?

There isn't one number for every chip. The best guide is your processor's Thermal Junction Maximum, usually written TJMax: the highest temperature the manufacturer rates it to run at. Reach it and the CPU throttles. Stay under it and you're inside the safe range, even when the number looks high.

These figures come from AMD's and Intel's official product pages as of November 2025. For any other chip, look up your exact model on the manufacturer's site.

What should my CPU temperature be at idle and under load?

The two readings tell you different things, so it helps to know what normal looks like for each.

Idle temperatures vary between builds, so don't compare yours with a friend's down to the degree. The 70°C idle line is the one to watch.

How do I check if my PC is overheating?

Step 1: Read the idle temperature in the BIOS

The BIOS is the cleanest place to check, because the CPU is under almost no load there. On most motherboards you get in by pressing Delete at the startup splash screen. Some boards use F2 instead.

A reading in the 30s means the cooler is doing its job. A much higher than normal reading, 70°C or more on startup, means there's likely a hardware issue with the cooler.

Step 2: Watch it under load

Back in Windows, open a monitoring tool such as NZXT CAM and keep an eye on CPU temperature while you play. You're looking for the temperature pinned at your chip's TJMax while performance falls off.

Different monitoring tools sample at different rates, so two apps can show slightly different numbers at the same moment. That doesn't make either one wrong. Pick one tool and stick with it.

What causes a CPU to overheat?

Three things cause most of it:

• The cooler is too small for the CPU. A 120mm cooler on a high-performance chip like a Ryzen 9 or Core Ultra 9 can run out of capacity under sustained load.
• Dust is blocking the airflow. Dust and debris packed into the radiator stop air from flowing through it.
• Part of the cooler has failed. A dead fan or a failing pump can't move the heat away.

On a new build or one you've just changed, check two more. A radiator mounted entirely below the pump lets air collect in the pump, which cuts its performance (our guide to where to mount an AIO radiator explains the rule). And a case with too little airflow for what's inside it makes every cooler work harder, which is where how many case fans you need comes in.

How do I fix an overheating PC?

Work through these in order. The first two cost nothing.

1. Clean it. Power down, unplug and clear the dust out of the radiator, the fans and the case's dust filters.
2. Check the fans and the pump. Make sure every fan spins and the pump reports an RPM. If you have a Kraken, our guide to whether your AIO cooler is failing walks through the pump checks step by step.
3. Check the mounting. The highest point of the radiator should sit above the pump cap.
4. Size up the cooler. If everything above checks out and temperatures are still pinned at TJMax, the cooler is undersized for the CPU. A bigger radiator gives the heat more surface to leave through. Our AIO size guide covers which size suits which build.

If your PC is still under warranty, contact NZXT Support before you remove the cooler. NZXT prebuilt PCs carry a standard 2-year limited warranty.

Can other parts of my PC overheat?

Yes, though it's much less common and harder to spot than a hot CPU.

These overheats are rare and sometimes need a replacement part to confirm. If your screen is showing strange shapes or colors, start with our GPU artifacting guide. If you suspect one of these parts on a PC that's still under warranty, our support team can help.

Frequently asked questions

Is 90°C too hot for a CPU?

Not automatically. Check your chip's TJMax first. The current AMD and Intel processors in the table above are rated to 95°C-105°C, so reaching the 90s under a heavy load is within spec for them. Sitting at the limit while performance drops is the part to fix.

What's a normal idle CPU temperature?

It varies between builds. The BIOS reading in the screenshot above is 31°C, which is a properly cooled system. The warning sign is a much higher than normal reading, 70°C or more, straight after startup.

Why do different apps show different CPU temperatures?

Each monitoring tool samples your hardware at its own rate, so readings won't line up exactly. That doesn't mean one is more accurate than another. If you see a big gap that doesn't make sense, send a ticket to our support team.

Can overheating damage my CPU?

The CPU protects itself, first by throttling and then by shutting down through Over-temperature Protection. Those safeguards are there to prevent damage, but a PC that keeps hitting them is telling you something needs attention.

My PC turns off during games. Is it overheating?

It can be. Over-temperature Protection shuts the system down when throttling can't keep up. A power supply problem can cause sudden shutdowns too, so check the CPU temperature first and then work through our random shutdowns guide.

Will a bigger AIO fix my temperatures?

If the cooler is healthy and simply too small for the CPU, a larger radiator helps. It won't fix a failed pump or a radiator clogged with dust, so rule those out first.

Still stuck?

Send our team your BIOS idle temperature, your CPU model and your cooler and they can usually point you in the right direction. Reach them at NZXT Support.